Sea spray aerosol organic enrichment, water uptake and surface tension effects
The aerosol-driven radiative effects on marine low-level cloud represent a large uncertainty in climate simulations, in particular over the Southern Ocean, which is also an important region for sea spray aerosol production. Observations of sea spray aerosol organic enrichment and the resulting impac...
Published in: | Atmospheric Chemistry and Physics |
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Main Authors: | , , , , , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
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Copernicus GmbH
2020
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Subjects: | |
Online Access: | https://doi.org/10.5194/acp-20-7955-2020 http://ecite.utas.edu.au/145934 |
id |
ftunivtasecite:oai:ecite.utas.edu.au:145934 |
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openpolar |
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Open Polar |
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eCite UTAS (University of Tasmania) |
op_collection_id |
ftunivtasecite |
language |
English |
topic |
Earth Sciences Atmospheric sciences Atmospheric aerosols |
spellingShingle |
Earth Sciences Atmospheric sciences Atmospheric aerosols Cravigan, LT Mallet, MD Vaattovaara, P Harvey, MJ Law, CS Modini, RL Russell, LM Stelcer, E Cohen, DD Olsen, G Safi, K Burrell, TJ Ristovski, Z Sea spray aerosol organic enrichment, water uptake and surface tension effects |
topic_facet |
Earth Sciences Atmospheric sciences Atmospheric aerosols |
description |
The aerosol-driven radiative effects on marine low-level cloud represent a large uncertainty in climate simulations, in particular over the Southern Ocean, which is also an important region for sea spray aerosol production. Observations of sea spray aerosol organic enrichment and the resulting impact on water uptake over the remote Southern Hemisphere are scarce, and therefore the region is under-represented in existing parameterisations. The Surface Ocean Aerosol Production (SOAP) voyage was a 23 d voyage which sampled three phytoplankton blooms in the highly productive water of the Chatham Rise, east of New Zealand. In this study we examined the enrichment of organics to nascent sea spray aerosol and the modifications to sea spray aerosol water uptake using in situ chamber measurements of seawater samples taken during the SOAP voyage. Primary marine organics contributed up to 23 % of the sea spray mass for particles with diameter less than approximately 1 m and up to 79 % of the particle volume for 50 nm diameter sea spray. The composition of the submicron organic fraction was consistent throughout the voyage and was largely composed of a polysaccharide-like component, characterised by very low alkane-to-hydroxyl-concentration ratios of approximately 0.10.2. The enrichment of organics was compared to the output from the chlorophyll- a -based sea spray aerosol parameterisation suggested by Gantt etal. ( 2011 ) and the OCEANFILMS (Organic Compounds from Ecosystems to Aerosols: Natural Films and Interfaces via Langmuir Molecular Surfactants) models. OCEANFILMS improved on the representation of the organic fraction predicted using chlorophyll a , in particular when the co-adsorption of polysaccharides was included; however, the model still under-predicted the proportion of polysaccharides by an average of 33 %. Nascent 50 nm diameter sea spray aerosol hygroscopic growth factors measured at 90 % relative humidity averaged 1.930.08 and did not decrease with increasing sea spray aerosol organic fractions. The observed hygroscopicity was greater than expected from the assumption of full solubility, particularly during the most productive phytoplankton bloom (B1), during which organic fractions were greater than approximately 0.4. The water uptake behaviour observed in this study is consistent with that observed for other measurements of phytoplankton blooms and can be partially attributed to the presence of sea salt hydrates, which lowers the sea spray aerosol hygroscopicity when the organic enrichment is low. The inclusion of surface tension effects only marginally improved the modelled hygroscopicity, and a significant discrepancy between the observed and modelled hygroscopicity at high organic volume fractions remained. The findings from the SOAP voyage highlight the influence of biologically sourced organics on sea spray aerosol composition; these data improve the capacity to parameterise sea spray aerosol organic enrichment and water uptake. |
format |
Article in Journal/Newspaper |
author |
Cravigan, LT Mallet, MD Vaattovaara, P Harvey, MJ Law, CS Modini, RL Russell, LM Stelcer, E Cohen, DD Olsen, G Safi, K Burrell, TJ Ristovski, Z |
author_facet |
Cravigan, LT Mallet, MD Vaattovaara, P Harvey, MJ Law, CS Modini, RL Russell, LM Stelcer, E Cohen, DD Olsen, G Safi, K Burrell, TJ Ristovski, Z |
author_sort |
Cravigan, LT |
title |
Sea spray aerosol organic enrichment, water uptake and surface tension effects |
title_short |
Sea spray aerosol organic enrichment, water uptake and surface tension effects |
title_full |
Sea spray aerosol organic enrichment, water uptake and surface tension effects |
title_fullStr |
Sea spray aerosol organic enrichment, water uptake and surface tension effects |
title_full_unstemmed |
Sea spray aerosol organic enrichment, water uptake and surface tension effects |
title_sort |
sea spray aerosol organic enrichment, water uptake and surface tension effects |
publisher |
Copernicus GmbH |
publishDate |
2020 |
url |
https://doi.org/10.5194/acp-20-7955-2020 http://ecite.utas.edu.au/145934 |
long_lat |
ENVELOPE(-67.150,-67.150,-66.967,-66.967) |
geographic |
Langmuir New Zealand Southern Ocean |
geographic_facet |
Langmuir New Zealand Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_relation |
http://ecite.utas.edu.au/145934/1/145934 - Sea spray aerosol organic enrichment.pdf http://dx.doi.org/10.5194/acp-20-7955-2020 Cravigan, LT and Mallet, MD and Vaattovaara, P and Harvey, MJ and Law, CS and Modini, RL and Russell, LM and Stelcer, E and Cohen, DD and Olsen, G and Safi, K and Burrell, TJ and Ristovski, Z, Sea spray aerosol organic enrichment, water uptake and surface tension effects, Atmospheric Chemistry and Physics, 20, (13) pp. 7955-7977. ISSN 1680-7316 (2020) [Refereed Article] http://ecite.utas.edu.au/145934 |
op_doi |
https://doi.org/10.5194/acp-20-7955-2020 |
container_title |
Atmospheric Chemistry and Physics |
container_volume |
20 |
container_issue |
13 |
container_start_page |
7955 |
op_container_end_page |
7977 |
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1766207890696175616 |
spelling |
ftunivtasecite:oai:ecite.utas.edu.au:145934 2023-05-15T18:26:04+02:00 Sea spray aerosol organic enrichment, water uptake and surface tension effects Cravigan, LT Mallet, MD Vaattovaara, P Harvey, MJ Law, CS Modini, RL Russell, LM Stelcer, E Cohen, DD Olsen, G Safi, K Burrell, TJ Ristovski, Z 2020 application/pdf https://doi.org/10.5194/acp-20-7955-2020 http://ecite.utas.edu.au/145934 en eng Copernicus GmbH http://ecite.utas.edu.au/145934/1/145934 - Sea spray aerosol organic enrichment.pdf http://dx.doi.org/10.5194/acp-20-7955-2020 Cravigan, LT and Mallet, MD and Vaattovaara, P and Harvey, MJ and Law, CS and Modini, RL and Russell, LM and Stelcer, E and Cohen, DD and Olsen, G and Safi, K and Burrell, TJ and Ristovski, Z, Sea spray aerosol organic enrichment, water uptake and surface tension effects, Atmospheric Chemistry and Physics, 20, (13) pp. 7955-7977. ISSN 1680-7316 (2020) [Refereed Article] http://ecite.utas.edu.au/145934 Earth Sciences Atmospheric sciences Atmospheric aerosols Refereed Article PeerReviewed 2020 ftunivtasecite https://doi.org/10.5194/acp-20-7955-2020 2021-09-06T22:17:41Z The aerosol-driven radiative effects on marine low-level cloud represent a large uncertainty in climate simulations, in particular over the Southern Ocean, which is also an important region for sea spray aerosol production. Observations of sea spray aerosol organic enrichment and the resulting impact on water uptake over the remote Southern Hemisphere are scarce, and therefore the region is under-represented in existing parameterisations. The Surface Ocean Aerosol Production (SOAP) voyage was a 23 d voyage which sampled three phytoplankton blooms in the highly productive water of the Chatham Rise, east of New Zealand. In this study we examined the enrichment of organics to nascent sea spray aerosol and the modifications to sea spray aerosol water uptake using in situ chamber measurements of seawater samples taken during the SOAP voyage. Primary marine organics contributed up to 23 % of the sea spray mass for particles with diameter less than approximately 1 m and up to 79 % of the particle volume for 50 nm diameter sea spray. The composition of the submicron organic fraction was consistent throughout the voyage and was largely composed of a polysaccharide-like component, characterised by very low alkane-to-hydroxyl-concentration ratios of approximately 0.10.2. The enrichment of organics was compared to the output from the chlorophyll- a -based sea spray aerosol parameterisation suggested by Gantt etal. ( 2011 ) and the OCEANFILMS (Organic Compounds from Ecosystems to Aerosols: Natural Films and Interfaces via Langmuir Molecular Surfactants) models. OCEANFILMS improved on the representation of the organic fraction predicted using chlorophyll a , in particular when the co-adsorption of polysaccharides was included; however, the model still under-predicted the proportion of polysaccharides by an average of 33 %. Nascent 50 nm diameter sea spray aerosol hygroscopic growth factors measured at 90 % relative humidity averaged 1.930.08 and did not decrease with increasing sea spray aerosol organic fractions. The observed hygroscopicity was greater than expected from the assumption of full solubility, particularly during the most productive phytoplankton bloom (B1), during which organic fractions were greater than approximately 0.4. The water uptake behaviour observed in this study is consistent with that observed for other measurements of phytoplankton blooms and can be partially attributed to the presence of sea salt hydrates, which lowers the sea spray aerosol hygroscopicity when the organic enrichment is low. The inclusion of surface tension effects only marginally improved the modelled hygroscopicity, and a significant discrepancy between the observed and modelled hygroscopicity at high organic volume fractions remained. The findings from the SOAP voyage highlight the influence of biologically sourced organics on sea spray aerosol composition; these data improve the capacity to parameterise sea spray aerosol organic enrichment and water uptake. Article in Journal/Newspaper Southern Ocean eCite UTAS (University of Tasmania) Langmuir ENVELOPE(-67.150,-67.150,-66.967,-66.967) New Zealand Southern Ocean Atmospheric Chemistry and Physics 20 13 7955 7977 |